Method of controlling weeds



United States PatentO 3,298,819 METHOD OF CONTROLLING WEEDS Llewellyn W. Fancher, Lafayette, Calif., and Chester L. Dewald, Houston, Tex., assignors to Staufier Chemical Company, New York, N.Y., a corporation of Delaware No Drawing. Original application May 28, 1963, Ser. No. 283,709, now Patent No. 3,205,253, dated Sept. 7,

1965. Divided and this application July 16, 1965, Ser.

8 Claims. (Cl. 71-2.6)

(NHrCl) NaGl The beta-chloro intermediates only have been indicated in the above reaction merely for economic reasons. However, the beta-bromo and beta-iodo intermediates will also yield the equivalent phosphate derivatives.

The Completeness of the above reaction is dependent upon the type of solvent used. In general, polar solvents are better than non-polar solvents and certain catalysts such as tertiary amines and dimethyl formamide aid in bringing the reaction to completion.

The following non-limiting examples illustrate the preparation of this class of compounds:

Example 1--N-(beta-0,0-diethyldithiophosphorylelhyl)- benzene sulfonamide yielded after a four hour reflux period, 20.8 g. (88% of acre.

theory) of viscous product. n =l.5428.

Analysis Sulfur, Nitrogen, Phosphorus,

Percent Percent Percent Theory 24. 15 3. 54 7.79 Found 25. 42 3. 6.72

By analogous procedures the following additional compounds were prepared:

R and R:

n-Butyl 0 p-Ghlorophenyl 3,4-diehlorophenyl- Ethyl-isopropyl Methyl-isopropyl Ethyl-n-propyl Methyl-ethyl The compounds of the present invention are excellent herbicides as will be indicated by the test results shown hereinafter wherein the compounds of the present invention are used as pre-emergence herbicides.

In making the tests for pre-emergence application, seeds of the test weed species are planted in individual rows one-half inch deep in Santa Cruz sandy loam soil contained in '8" x 12" metal flats. Enough seeds are planted to give about 30 to .50 plants of each weed species in each fiat. The flats are watered after planting and the following day each fiat is sprayed at a rate of 5 pounds of the compound under test in gallons of solution per The spraying is conducted as the flat is carried by a moving belt under a sprayer to simulate field spraying conditions. Two weeks later the degree of weed control is' determined by comparing the amount of germination and growth of each weed in the treated flats with the weeds in several untreated control flats.

The following chart shows the results of such tests.

A mixture Of 116 g. (0.53 M) Of N-(betachloroethyl)- Foxtail Annual Crab Grass Nut Grass benzene sulfonamide, 162.4 g. (0.8 M) of ammonium- 50 Com Bluegrass diethyldithiophosphate and 250 ml. of methyl ethyl ketone pound P P P P er- 81'- 6!- erwas stlrred and refluxed for four hours. The solvent was cent cent Gr Gent Gr cent Gr removed on a steam bath with an air et, and the residue Ge Ge Ge Ge taken up in ethyl ether and washed three times with dilute aqueous sodium chloride. The ether solution was dried Inn 100 1m 0 0 over anhydrous magnesium sulfate, filtered and the ether g2; igg 8 ii if? removed on the steam bath with an air jet. The viscous gm; 100 10 50 2mg 30 1115 product weighed 170 g. of theory). n 1.5468. 5,115 70 7 10 5ms 100 10 100 10 10 100 10 0 Analysis Sulfur, Nitrogen, Phosphorus, 10 30 3 0 10 Percent Percent Percent 0 00 10 50 7 Theory 26.00 3. 79 g, 39 Legends: Gegermination. Gr-growth (on a rating system of 0 to 10; Found 25.69 3.88 7,79 ll death or very severe effects, 10=n0nnal), iii-malformation, ch--- 0 OIOSlS.

Example 2-N-(beta-0,a-diisopropyldithiophosphoryl)- benzene sulfonamide By an analogous procedure as for Example 1, a mixture of 13.2 g. (0.06 M) of N-(beta-chloroethyl)-benzenesulfonamide, 25.2 g. (0.1 M) of potassium-diisopropyl dithiophosphate and 100 ml. of methyl ethyl ketone Patented Jan. 17, 1967 3,2es,s 19

The flats are watered after planting and the following day each flat is sprayed at a rate of 20 pound s of the com-v pound under test in 80 gallons of solution per acre. A No. 152 DeVilbiss atomizer is used to spray the solution on the soil surface. Two weeks later the degree of weed control is determined by comparing the amount of germination and growth of each weed in the treated flats with the weeds in several control flats.

The results of these tests are as follows:

Foxtail Annual Water grass Pigweed Bluegrass C ompound Per- Per- Per- Percent Gr cent Gr cent Gr cent Gr Ge Ge Ge Ge 15 0 20 2:1 0 a. 16 50 5 20 2bz 50 5 I 20 2b;

Legends: Gegerminati0n, Gr-growth (on a0 to scale; 0=deathor very severe effect, 10=n0rmal), bburn, ddesiccation. Compounds 17 through 20 were tested in the same manner as were compounds 15 and 16. The test rate, however, was 2 lbs/acre and the weed' species tested were crab grass, foXtail and water grass. The results were as Legends: Gegermination, Grgrowth (on a rating system of 0 to 10; 0=death or very severe effects, 10=n0rma1).

We claim:

1. The method of controlling weeds comprising applying to the soil a herbicidally effective amount of a compound of the formula:

wherein R and R are lower alkyl radicals and X is .lower alkyl and nitro.

2. The method of controlling weeds comprising applying to the soil a herbicidally effective amount of the compound N- (beta-o,o-diethyldithiophosphorylethyl) -benzene sulfonamide.

3, The method of controlling weeds comprising'applying to the soil at herbicidally effective amount of the compound N-(beta 0,0 diisopropyldithiophosphorylethyl)- benzene sulfonamide.

4. The method of controlling weeds comprising applying to the soil a herbicidally eiTective amount of the compound N- beta-o,o-diisopropyldithiophosphorylethyl) -2,5- dichlorobenzene sulfonamide.

5. The method of controlling weeds comprising applying to the soil a herbicidally eifective amount of the compound N (beta 0,0 di-n-propyldithiophosphorylethyl)- benzene sulfonamide.

6. The method of controlling weeds comprising applying to the soil a herbicidally effective amount of the compound N- (beta-o,o-di-n-propyldithiophosphorylethyl -2,5- dichlorobenzene sulfonamide.

7. The method of controlling weeds comprising applying to the soil a herbicidally effective amount of the compound N- (beta-o-ethyl-o-isopropy1dithiophosphorylethyl) benzene sulfonamide.

8. The method of controlling weeds comprising applying to the soil a herbicidally effective amount of the compound N-(beta-o-methyl-o-isopropyldithiophosphorylethyl)-benzene sulfonamide.

References Cited by the Examiner UNITED STATES PATENTS 2,705,195 3/1955 Cupery et a1 71-2.6 2,744,819 5/1956 Toorman 712.6 2,803,580 8/1957 Metivier 260461 2,862,019 11/1958 Schrader 260-461 2,865,801 12/1958 Baker et al 260461 X 2,894,017 7/1959 Schegk et a1 260461 3,005,004 10/ 1961 Berkelhammer 260461 FOREIGN PATENTS 927,092 4/ 1955 Germany.

LEWIS GOTTS, Primary Examiner.

J. O. THOMAS, JR., Examiner. 

1. THE METHOD OF CONTROLLING WEEDS COMPRISING APPLYING TO THE SOIL A HERBICIDALLY EFFECTIVE AMOUNT OF A COMPOUND OF THE FORMULA: 